Since landing in 2012, the Curiosity rover has seen a lot of varied terrain within Gale crater, including ancient riverbed gravel, sandstone and mudstone rock outcrops, sand ripples finely sculpted by the Martian wind, and, of course, Mount Sharp looming above. Now the rover has reached a new type of landform previously only seen from orbit: a field of huge sand dunes.
Mars is often referred to as a desert world, being bone-dry for the most part, with dust and sand blanketing most of the surface. Some regions are covered in vast sand dunes, reminiscent of deserts like the Sahara on Earth, only much colder. Gale crater, where the Curiosity rover landed in 2012, features extensive dune fields around the base of Mount Sharp, and the rover is now approaching some of them for the first time; their dark color makes them stand out starkly against the surrounding terrain. These dunes are also still active, meaning they are still mobile and shaped by the wind, not just old “fossil” (petrified) dunes which are no longer active.